From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Stephen C. Tweedie" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <14517.8311.194809.598957@dukat.scot.redhat.com> Date: Thu, 24 Feb 2000 12:13:43 +0000 (GMT) Subject: Re: mmap/munmap semantics In-Reply-To: <20000224033502.B6548@pcep-jamie.cern.ch> References: <14516.11124.729025.321352@dukat.scot.redhat.com> <20000224033502.B6548@pcep-jamie.cern.ch> Sender: owner-linux-mm@kvack.org Return-Path: To: Jamie Lokier Cc: "Stephen C. Tweedie" , Richard Guenther , Linux Kernel List , glame-devel@lists.sourceforge.net, Linux-MM List-ID: Hi, On Thu, 24 Feb 2000 03:35:02 +0100, Jamie Lokier said: > I don't think MADV_DONTNEED actually drops privately modified data does > it? Yes, it does. From the DU man pages: MADV_DONTNEED Do not need these pages The system will free any whole pages in the specified region. All modifications will be lost and any swapped out pages will be discarded. Subsequent access to the region will result in a zero-fill-on-demand fault as though it is being accessed for the first time. Reserved swap space is not affected by this call. Regarding the other half of the problem --- zeroing out a portion of a file without further IO --- the splice code I hope to have using kiobufs in 2.5 will allow this to be done very easily. You'll be able to take a region of /dev/zero and splice it into your open file with zero-copy. --Stephen -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux.eu.org/Linux-MM/